Graft-versus-host reactivity of mouse thymocytes: effect of in vitro treatment with anti-TL serum.

The lymph ducts efferent from prefemoral nodes of sheep were cannulated and the lymph flow monitored during immune responses to injected allogeneic lymphocytes or xenogeneic murine P815 mastocytoma cells. Changes in the lymph began 5–6 days after injection of allogeneic cells but at 3–4 days after injection of xenogeneic cells, in both systems the number of large cells in the lymph increased to reach peak values of up to 40% of the total. The in vitro cytotoxic activity of lymph cells, cell supernatants, or cell free lymph was determined by measuring the release of ⁵¹Cr from prelabeled target lymphocytes or P815 cells. The cytotoxic mechanisms that were detected in the allogeneic and xenogeneic systems were similar; in both cases the lymph cells were cytotoxic only during the large cell response, and when the immunoblast numbers had returned to normal levels in the lymph no further cell-mediated cytotoxic effects were detected. During the blast response lymphocytes alone caused some target cell damage but their cytotoxic effector function was greatly increased in cultures containing complement or normal blood white cells. It was concluded that the lymph immunoblasts caused some target cell damage by direct action, but the majority of their cytotoxic activity was associated with synthesis and secretion of complement-dependent antibody (C.D.A.) and leukocyte-dependent antibody (L.D.A.).     

Toxic effect of lithium in mouse brain

The effect of lithium ion on glucose oxidation in the cerebrum and cerebellum of mice was measured in vitro by the conversion of isotopic glucose into 14CO2/mg wet weight. Glucose utilization is unaffected by lowest lithium dosage but is inhibited by high lithium concentrations (197-295 mM). Chronic administration of lithium to adult mice decreased the DNA content of the cerebrum and cerebellum at concentrations of 80 and 108 mM. The DNA content of selected postnatal stages of cerebrum and cerebellum was measured starting on Day 1 or 2. This served as another parameter to evaluate glucose oxidation studies at these ages. On the basis of wet weight, both brain parts of neonates of ages 1 and 10 days were approximately one-half that of the adult counterparts. On the basis of DNA content, the cerebrum enhanced its glucose utilization twofold from Day 1 to Day 10 and tripled its utilization from Day 10 to Day 20. The glucose utilization by cerebrum at Day 20 is similar to adult values. In contrast, glucose oxidation in the cerebellum remained relatively constant throughout the postnatal growth. The relative susceptibility of the two brain parts is discussed.     

The effect of lithium chloride treatment on cell-mediated immunity in mice.

The immunomodulatory effect of lithium chloride (LiCl) administered i.p. to adult mice (150 mg/kg/day) on cellular immunity in vivo was investigated. A short (6-day) treatment with LiCl of either spleen cell donors in semiallogeneic or xenogeneic GVH reaction, or recipients in semiallogeneic HVG reaction, significantly diminished the early sings of local cell-mediated immunity. A short-term LiCl treatment of donor mice also abrogated systemic GVH reaction in newborn F1 recipients, while a treatment prolonged for 20 days did not alter the high GVH response of spleen cells typical for untreated donors. Thus, a striking time-dependent efficacy of LiCl on the reduction of GVH reaction was found.     

In vitro maintenance of differentiation marker synthesis by subpopulations of mouse thymocytes

Mouse thymocyte populations enriched in functionally incompetent, “immature” cells on the one hand, or in competent “mature” cells on the other hand, express different steady-state levels of certain surface antigens and marker enzymes. In the cases of the glycoproteins H-2 (K and D), Qa, and TL, and the DNA polymerase terminal deoxynucleotidyl transferase (TdT), these levels reflect different rates of de novo synthesis in the two populations. Thus each population appears to manifest a characteristic pattern of synthetic rates for the various products relative to total protein synthesis. To investigate the maintenance of these patterns, enriched pools of “immature” and “mature” thymocytes were incubated in vitro for 24 h, and the rates of product synthesis before and after culture were compared. H-2 synthesis, initially most rapid in the mature cells, continued to be made at the highest rate in this population. TdT synthesis, a characteristic activity of the immature cells, was not induced in the mature cells, but proceeded at an increased relative rate in the immature population. Therefore, the differences between the rates of H-2 and TdT synthesis were stable properties of the two thymocyte populations. Another marker of immature cells, TL, did not continue to be produced in parallel with TdT. Rather, its synthesis was selectively curtailed in relation to the continuing protein synthesis in the immature cultures. This non-coordinate regulation of TL and TdT production in immature thymocytes may be due to several mechanisms. These are discussed with regard to their implications for pathways of thymocyte maturation.     

Effect of lithium carbonate on mouse and rat embryos in vitro

Lithium is effective in the treatment of manic-depressive psychosis but is suspected to be a developmental toxicant in humans. It is a developmental toxicant in mice and rats in vivo, but at human therapeutic serum levels of 0.6-1.6 meq/L, rats appear to be more sensitive to the effects of the drug than do mice. The species susceptibility to lithium-induced defects was evaluated by using a rodent whole embryo culture system employing mouse and rat embryos treated at comparable developmental stages. Mouse embryos were cultured on gestational days 8-10, and rat embryos were cultured on gestational days 10-12. Care was taken to insure that all embryos had 10 +/- 2 somite pairs at the beginning of the culture period. Embryos were cultured for 44 hours in rat serum to which lithium was added to attain final drug concentrations of 0.6, 1.2, 1.8, 2.4, or 5.0 meq/L. Control embryos were treated with distilled water, which served as the vehicle. In rats, lithium induced significant decreases in various parameters at 1.8, 2.4, and 5.0 meq/L; no malformations were observed in rats of this stage. In mice, significant decreases occurred at 2.4 and 5.0 meq/L, and embryos treated at the highest concentration had a significantly increased frequency of open neural tubes. Rat embryos were also cultured with lithium on gestational days 9-11. The lowest dose producing developmental toxicity at this stage was 0.6 meq/L. Open neural tubes were present among younger rat embryos; however, this defect occurred in all groups, including the control group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of dimethyl sulfoxide-induced Friend erythroleukemia cell differentiation in vitro by lithium chloride

This report describes the ability of ultra-pure lithium chloride (LiCl) to influence the growth kinetics and differentiation of Friend erythroleukemia cells in vitro. LiCl (0.2-50 mEq/l) was effective in reducing the ability of Friend cells to grow in liquid suspension culture (p less than or equal to 0.001). In addition, the capacity of these erythroleukemic cells to respond to the inducing agent dimethyl sulfoxide (DMSO) was also significantly reduced (p less than or equal to 0.001). These results demonstrate that LiCl can influence not only the proliferation of erythroleukemia cells but also their subsequent differentiation after exposure to such chemical inducers.     

The effect of lithium chloride on the biooxidation of aqueous methanol/acetone mixtures

Lithium chloride, more specifically the lithium cation, has been implicated in interference in biological systems. In the case of Escherichia coli, interference involves the Na+(Li+)/H+ antiporter transport system. The study reported here concerns the effects of LiCl on a mixed enrichment culture that is able to biodegrade both methanol and acetone under aerobic conditions. The results obtained using unsteady state continuous flow culture techniques demonstrate a significant disruptive effect of LiCl on culture performance. In addition, a reduction in the substrate-based biomass yield coefficient, which is a clear advantage as far as biotreatment process performance is concerned, also occurs. The ultimate fate of the LiCl was not determined.     

The effect of hyaluronan on mouse intramembranous osteogenesis in vitro

Hyaluronan (HA) is an almost ubiquitous component of extracellular matrices. Early in embryogenesis mesenchymal cells migrate, proliferate and differentiate, in part, because of the influence of HA. Because many of the features of embryogenesis are revisited during wound repair, including bone fracture repair, this study was initiated to evaluate whether HA has an effect on calcification and bone formation in an in vitro system of osteogenesis. Enzyme-digested calvarial mesenchymal cells from 13-day-old mouse embryos were cultured in BGJb medium with rooster comb hyaluronan in seven different molecular weights (30, 40, 90, 160, 550, 660, and 1300 kDa). The dosages for each molecular weight were 0.5, 1.0 and 2.0 mg/ml. HA was added once to the medium at the plating of cells. After 10 days in culture, with low molecular weight hyaluronan (30 and 40 kDa) bone colonies were identifiable on a base of confluent fibroblasts. The number of colonies was larger than controls, particularly in the 1.0 and 2.0 mg/ml dosages of both 30 and 40 kDa of HA. Hyaluronan of high molecular weight, no matter what the dose, showed no significant bone colony formation, with apparent cell growth inhibition. Higher molecular weights were thereafter not included in this study. No statistically significant difference in the size of colonies was found when compared to controls in the 30 and 40 kDa bone colonies no matter what the dose.     

In vitro andin vivo effect of chloropromazine,imipramine and lithium chloride on monoamine oxidase activity in rat brain mitochondria

Chloropromazine (CPZ) and imipramine at a concentration of 1×10^–3 M inhibit rat brain mitochondrial monoamine oxidase activity in vitro by 70 and 55% respectively, while lithium, even at a concentration of 0.05 M, inhibits the activity of this enzyme very negligibly (4%). In vivo, these drugs at a dose level of 56 mg CPZ, 76 mg Jimipramine and 76 mg lithium chloride/Kg body wt., did not cause any observable variation from normal in brain mitochondrial monoamine oxidase activity.To whom correspondence should be addressed.     

Role of EGF receptor tyrosine kinase activity in antiapoptotic effect of EGF on mouse hepatocytes

The apoptotic Fas pathway is potentially involved in the pathogenesis of liver diseases. Growth factors, such as epidermal growth factor (EGF), can protect cells against apoptosis induced by a variety of stimuli, including Fas receptor stimulation. However, the underlying mechanisms of this protection have yet to be determined. We investigated the involvement of EGF receptor (EGFR) tyrosine kinase (TK) activity in the antiapoptotic effect of EGF on primary mouse hepatocyte cultures. Cells undergoing apoptosis after treatment with anti-Fas antibody were protected by EGF treatment. This protection was significantly but partially decreased when cells were treated with two specific inhibitors of the TK activity of EGFR. Evaluation of the efficacy of these compounds indicated that they were able to abolish EGFR autophosphorylation and postreceptor events such as activation of mitogen-activated protein kinases and the phosphatidylinositol 3'-kinase pathways as well as increases in Bcl-x(L) mRNA and protein levels. This leads us to postulate that EGF exerts its antiapoptotic action partially through the TK activity of EGFR. In addition, our results suggest that Bcl-x(L) protein upregulation caused by EGF is linked to the TK activity of its receptor.     

Erythropoietin has an antiapoptotic effect after myocardial infarction and stimulates in vitro aortic ring sprouting

Aims were to explore if darbepoietin-α in mouse can induce angiogenesis and if moderate doses after myocardial infarction stimulates periinfarct capillary and arteriolar densities, cell proliferation, and apoptosis. Myocardial infarction was induced by ligation of LAD. Mouse aortic rings (0.8 mm) were cultured in matrigel and the angiogenic sprouting was studied after addition of darbepoietin-α with and without VEGF-165. After 12 days the hemoglobin concentration was 25% higher in the darbepoietin-α treated mice than in the control group. No difference in capillary densities in the periinfarct or noninfarcted areas was seen with darbepoietin-α. Cell proliferation was about 10 times higher in the periinfarct area than in the noninfarcted wall. Darbepoietin-α treatment led to a decrease of cell proliferation (BrdU, (p < 0.02)) and apoptosis (TUNEL, p < 0.005) with about 30% in the periinfarct area. Darbepoietin-α and VEGF-165 both independently induced sprouting from aortic rings. The results suggest that darbepoietin-α can induce angiogenesis but that moderate doses after myocardial infarction are not angiogenic but antiapoptotic.     

The stimulatory effect of serum thymic factor (FTS) on spontaneous DNA synthesis of mouse thymocytes

Synthetic serum thymic factor (FTS), a T-cell differentiating factor, was studied for its ability to modify the spontaneous DNA synthetic activity of immature or immunocompetent T cells in vitro. In serum free RPMI 1640 medium, FTS stimulated [3H]thymidine incorporation into the DNA of young adult mouse thymocytes in a time and concentration dependent manner. One to 100 pg/ml FTS were the effective concentrations, and the stimulation appeared 3 h after the treatment. A comparable stimulation was noticed, but to a lesser extent, on cultured bone marrow cells. In contrast, no effect could be detected on spleen cells whatever time or concentrations were studied. Neither thymocytes treated in vitro with hydroxyurea nor the medullary, cortisol-resistant thymocytes were sensitive to FTS treatment. In contrast, thymocytes bearing receptor to peanut agglutinin (PNA+) were significantly stimulated with FTS, which suggested that the target population of FTS belongs to the maturing, non-immunocompetent thymocyte compartment.